During operation of a four stroke engine, each cylinder has a piston that undergoes an Otto cycle that has an intake, compression, combustion and expansion stroke. Typically, each piston of a multiple cylinder engine undergoes the various strokes at different times relative to other cylinders to facilitate smooth operation. As a result, when the engine stops, each piston may rest at different points in the Otto cycle within their respective cylinders.
Combustion occurs when a spark is delivered to a combination of gasoline and air present in a cylinder. When an engine is started, fuel is delivered sequentially to the cylinders. In some instances however, fuel may be delivered to a cylinder that does not have sufficient air to achieve combustion. As a result, the fuel does not combust.